The chemical explosive 3-nitro-1,2,4-triazol-5-one, more commonly known as NTO (see, U.S. Pat. No. 4,733,610 to Kien-Yin Lee et al. entitled “3-nitro-1,2,4-triazol-5-one, A Less Sensitive Explosive,” which issued on Mar. 29, 1988, which is hereby incorporated by reference herein for all that it discloses and teaches) has the chemical formula:
and can be prepared safely in high yield from inexpensive starting materials. It is a white crystalline compound, has a crystal density of 1.93 g/cm3, is moderately soluble in water, relatively acidic (pKa=3.67), and forms stable salts with mono- and bivalent metals, including potassium, sodium, lithium, magnesium, calcium, strontium, barium, manganese, iron, cobalt, nickel, copper, zinc, silver, and lead, and ammonium salts. It has found use as the gas generant for an azide-free formulation for inflatable vehicle safety device. See, for example, U.S. Pat. No. 6,123,790 for “Nonazide ammonium nitrate based gas generant compositions that burn at ambient pressure,” which issued to Norman H. Lundstrom et al. on Sep. 26, 2000; and U.S. Pat. No. 6,296,724 for “Gas generating composition for an inflatable vehicle occupant protection device,” which issued to Harold R. Blomquist on Oct. 2, 2001.
NTO has a calculated detonation velocity and detonation pressure (at crystal density) equivalent to that of RDX (cyclotrimethylenetrinitramine), and a low sensitivity to shock and impact. In fact, NTO is considered to be an insensitive high explosive (IHE), being less sensitive than RDX, TNT, and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) in all respects, and similar in sensitivity to TATB. See U.S. Pat. No. 6,547,899 for “Synthesis of Fine-Grained TATB,” which issued to Kien-Yin Lee et al. on Apr. 15, 2003, and which is hereby incorporated by reference herein for all that it discloses and teaches.
For applications requiring both operational safety and high performance, it is desirable to have the design and formulation of an IHE, yet enable the tuning of performance and sensitivity.
Incorporation of aluminum nanopowders in energetic materials has been demonstrated to increase the burn rate of propellants, (See, for example: Fang Chong and Li Shufen, “Experimental Research Of The Effects Of Superfine Aluminum Powders On The Combustion Characteristics Of NEPE Propellants,” Propellants, Explosives, Pyrotechnics 27, 34 (2002).), and improve the detonation performance of some high explosives (See, for example: H. E. Dorsett et al., “The Influence of Ultrafine Aluminum upon Explosives Detonation,” 28th Int. Pyrotechnics Seminar, Adelaide, Australia, Nov. 4-9, (2001).). In “A Technique To Prepare Aluminized Nanosized Explosives,” by A. N. Jigatch et al, 29th Int. Pyrotechnics Seminar, Westminster, Colo., USA, Jul. 14-19, 2002, the authors describe the preparation of HE-encapsulated aluminum using suspension atomization and drying. It is stated that mechanical mixing and pressing of micron-size explosive grains with aluminum nanopowders will not give a homogeneous distribution of aluminum particles in the pressed sample.
In the parent patent application, supra, the present inventors described the preparation of ultrafine NTO (UF-NTO) and its admixture with nanoAl powder by slow precipitation. The particle median of the UF-NTO was found to be greater than nanosize, and intimate mixing between NTO and nanoAl powder was not observed.
There remains a need for simple procedures for preparing homogeneous nanocomposites of high explosives with energetic inorganic nanoparticles having increased burn rate and improved detonation performance over known insensitive high explosive materials.
Accordingly, it is an object of the present invention to provide a method for preparing nanoparticles of materials.
Another object of the invention is to provide a method for preparing energetic nanopowders.
Yet another object of the invention is to provide a method for preparing nanocomposites of selected materials with nanoparticles.
Still another object of the present invention is to provide a method for preparing nanocomposites of energetic organic materials with energetic inorganic nanoparticles.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.